I am playing it on an iPhone 3G, not a GS, so I don’t have the faster processor. The game has not exhibited any real lagginess at all other than the slow initial load time. Do you have sufficient free space on your iPod Touch? The OS and apps will slow down significantly if you don’t have much free space left for caching.

I also own the DS version and it was one of the games I played most frequently on the DS. I have spent MANY hours playing this game on the DS and now the iPhone. I did not really compare difficulty – as you point out that’s difficult to ascertain, especially with differeng maps and placements of cities, but I have found other cities just as likely to “convert” as before – that doesn’t seem any different to me, but I will compare some more and possibly comment again. I will point out, however, that you can always adjust the level of difficulty up as desired.

I actually have found that I prefer the interface on the iPhone even though I found longer-distance moving of units more difficult. I find the interface layout to make more sense and I prefer they iPhone/iPodTouch version of unit options more straightforward than the DS version. I also find icons easier to differentiate on the iPhone screen than the DS screen, but these things are often a matter of personal taste.

Civilization Revolution is meant to be more of a “casual gaming” version of the original Civilization. It requires far less in terms of system resources and hence runs better on smaller and more mobile platforms. As a casual gamer, I find the iPhone version is better implemented. The DS version is perhaps, a little closer to the original in it’s interface.